Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Air flow and pressure fluctuations may result in compressor surge, leading to noise disturbances, and in more severe cases, performance issues and compressor degradation. Compressor surge may be controlled by opening one or more compressor recirculation valves in order to route compressed air back to the compressor inlet.
The inventors have recognized an issue with the above approach. Opening the compressor recirculation valve may reduce the amount of boost provided to the intake, thus reducing engine output. Further, the compressor recirculation valve may not provide adequate surge control under all conditions. Accordingly, in one embodiment, an engine method comprises during a first mode, decreasing a volume of a charge air cooler in response to a compressor operation upstream of the charge air cooler.
In this way, during conditions where compressor surge is likely to occur, the volume of the charge air cooler may be decreased to maintain the compressor operation outside of a surge region. In one example, the charge air cooler may include a valve configured to close during current or predicted compressor operation in the surge region, allowing the intake air to flow through a subset of the volume of the charge air cooler. The valve may be configured to open during compressor operation in a non-surge region, for example, directing the intake air through the entirety of the charge air cooler. By routing the intake air through only a portion of the volume of the charge air cooler instead of the entire volume during surge conditions, intake air flow velocity increases and compressor surge may be avoided.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.